1. Field
The present general inventive concept relates to a toner for developing an electrostatic image and a method of manufacturing the toner.
2. Discussion of the Background
A toner for developing an electrostatic image is used in a printing device that prints according to an electrophotographic and electrostatic image developing process.
Small particle size, narrow particle size distribution, wide color gamut, and lower fixing temperature are considered as important quality properties of a toner. The small particle size, narrow particle size distribution, and wide color gamut provide for obtaining a high quality printing image. The lower fixing temperature provides for reducing energy consumption for printing and for reducing emission of carbon dioxide. Of course, other quality properties, such as high temperature preservation, anti-cohesiveness, and charge stability are also important.
As a method of manufacturing a toner, a pulverizing process has been proposed. In the pulverizing process, excessive energy is consumed for manufacturing a toner having a small particle size, and controlling the morphology of the toner particles is very difficult. Also, a releasing agent or a pigment may be exposed on a surface of the toner, and thus, anti-cohesiveness and storage ability are degraded.
As another method of manufacturing a toner, an emulsion and aggregation (EA) process has been proposed. In the EA method, toner particles are grown through agglomeration of various raw material particles. Accordingly, in the EA process, quality properties, such as small particle size and narrow particle size distribution may be easily obtained, and also, controlling the morphology of toner particles is relatively easy. ° C.A toner manufactured by the EA process is referred to as a “polymerized toner”. In a conventional EA process, a styrene-acrylate copolymer is used as a binder resin. However, because a color toner is frequently used in various application fields, transparency and fixing temperature of the binder resin may be improved,
Toner particles having a resin layer (shell) on a surface of a coloring particle (core particle) that include a resin and a colorant to provide a polymerized toner that has a small amount of the colorant present at the surface of the toner particle; and that does not cause variation in image density, fogging, and changing of color of a color image due to the change of charging properties and developing ability even after the toner is used to form a color image for a long period of time under a humid atmosphere has been proposed. This method may increase charge uniformity between colors to some degree by pressing surface exposure of a pigment. However, for example, when a large amount of wax is included in the toner, the heat storage ability and anti-cohesiveness at a high temperature may be reduced due to a plasticizing effect caused by some degree of partial miscibility between a low molecular weight portion of wax and a resin.
A method of encapsulating a surface of a binder resin having a low glass transition temperature Tg with a binder resin having a slightly higher Tg has been proposed for a low temperature fixing. This method may provide a low temperature fixing property, but may not sufficiently provide a high temperature storage ability and a gloss property.